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Optocoupler

Discussion in 'Datasheets, Manuals and Component Identification' started by chaitrali, Jul 8, 2016.

  1. chaitrali

    chaitrali

    6
    0
    Jul 8, 2016
    hello,
    i am using MOC3021 optocoupler for dimming of the bulb.I have done it but if i change the another same MOC3021 i am observing different output
     
  2. Minder

    Minder

    2,876
    596
    Apr 24, 2015
    That is a random phase control triac driver, not really intended to drive a load directly and meant for control of AC loads.
    Are you switching the load with the opto?
    More info needed!
    Look up Fairchild app note AN-3006. For phase control .
    M.
     
    hevans1944 likes this.
  3. chaitrali

    chaitrali

    6
    0
    Jul 8, 2016
    i am driving the triac gate with the help of moc3021
     
  4. Minder

    Minder

    2,876
    596
    Apr 24, 2015
    That is a random phase opto couple and has to be synced to the zero cross over, either by logic or RC methods see the app note for both methods.
    Show your circuit.
    M.
     
    hevans1944 and Arouse1973 like this.
  5. chaitrali

    chaitrali

    6
    0
    Jul 8, 2016
    See the digram
     

    Attached Files:

  6. Minder

    Minder

    2,876
    596
    Apr 24, 2015
    You don't have any phase control circuitry?
    M.
     
  7. chaitrali

    chaitrali

    6
    0
    Jul 8, 2016
    no
     
  8. Minder

    Minder

    2,876
    596
    Apr 24, 2015
    Then you have no control if and where on the incoming phase where it is going to fire!
    M.
     
  9. hevans1944

    hevans1944 Hop - AC8NS

    4,257
    2,008
    Jun 21, 2012
    Even if the BC547 transistor collector were not wired to a pin that is not connected (NC) on the datasheet, the most this obsolete optocoupler would do is turn the triac on or off. No dimming effect will occur without some sort of phase control of the input pulse with respect to the AC power connected between HOT and NEUTRAL

    Collector of BC547 should connect to pin 2.(CATHODE) of the LED, with a current-limiting resistor in series between +3.3 V DC supply and pin 1 (ANODE) of the LED. Or Is that what the thick black vertical "wire" in the drawing is supposed to represent?

    See attached page from datasheet for application information.
     

    Attached Files:

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